Allergic reactions to cashew nuts (Anacardium occidentale), though relatively infrequent, can be varied and even life threatening reactions include contact or systemic dermatitis (to cardol and anacardic acid found in the cashew nut shell oil) (Marks et al. 1984), atopic dermatitis, and IgE-mediated systemic allergic reactions. (Burks et al. 1998; Tariq et al. 1996; Garcia et al. 2000) Pistachios and mangos are other edible members of the Anacardiaceae family and are allergenic with pistachio showing extensive in vitro and possible clinical cross-reactivity with cashews. (Fernandez, Fiandor, Martinez-Garate, and Martinez 1995) (Parra et al. 1993) (Quercia, Rafanelli, Marsigli, Foschi, and Stefanini 1999). Cashew nuts are widely used in snack foods and as an ingredient in a variety of processed foods such as “butters”, bakery and confectionery products.
We have recently demonstrated that the major IgE-reactive proteins in extracts of cashew nut are legumin-like proteins and 2S albumins as assessed by N-terminal and enzymatic fragment sequencing of native proteins. (Teuber, Sathe, Peterson, and Roux 2002) We have also constructed a cashew nut cDNA library and, upon initial screening, cloned and sequenced an allergen in the 7S superfamily, which includes vicilin-like and sucrose binding proteins. (Wang et al. 2002) Here, we present the sequence and characteristics of a second cDNA encoding protein, designated Ana o 2, which is a member of the legumin (11S globulin) family of seed storage proteins. We also describe its reaction with sera from cashew-allergic patients and map its linear epitopes.